Thank you all for your very helpful advice on the ht-dig search engine, and
I will try to RTFM in future...Now for a real tricky problem, which maybe
one of you will be able to solve.

I run a news website from Dublin - RTE News Online, it's on
http://www.rte.ie/news/. We are configuring ht-dig to run as our search
engine. One of the search functionalities that I wish to include is a date
range, which will restrict a search to stories say, between March 1999 and
February 2000.